FIG. 1 is a conceptual diagram illustrating an uplink data reporting method for use in a mobile communication system.
A variety of data can be reported to a Node-B, and a detailed description thereof will be exemplarily described with reference to CQI.
User Equipment (UE) 12 measures a downlink channel quality upon receiving signals from the Node-B 11. The User Equipment (UE) 12 reports the selected CQI value and/or a Carrier-to-Interference and Node Ratio (CINR) value to the Node-B 11 over an uplink control channel, such that the Node-B 11 can recognize the measured result. The Node-B 11 performs a variety of downlink scheduling actions using the CQI and/or CINR value, for example, UE selection and radio-resource assignment.
However, a communication system based on several frequency bands (e.g., Orthogonal Frequency Division Multiplexing (OFDM) system) is unable to accurately estimate the channel quality status of some frequency bands (i.e., a frequency band divided to acquire the CQI) contained in a total frequency band upon receipt of a single CQI report corresponding to the total frequency band. Therefore, the above-mentioned communication system is also unable to schedule a downlink of each frequency band, such that it mist receive the CQI for each frequency band.
In the meantime, a Multiple Input Multiple Output (MIMO) system based on a plurality of antennas has been developed to effectively operate the OFDM system. The MIMO system provides a transmission bandwidth, and at the same time increases an amount of the CQI to be reported to the Node-B 11. However, physical channel resources required for reporting the CQI are restricted, such that the MIMO system has difficulty in effectively transmitting the increased CQI.
In order to prevent a control-signal overhead such as the CQI from abruptly increasing, a variety of methods have been proposed as follows. A first method measures a channel quality for each unit frequency band, and transmits CQI values of only the best frequency bands from among all the frequency bands to a destination. A second method groups several frequency bands, and transmits only one average CQI to a destination. A third method reduces the CQI length.